1. Field
The disclosed concept pertains generally to filters and, more particularly, to filters for removing a fundamental frequency from an analog signal, such as, for example, a motor current. The disclosed concept also pertains to methods of removing a fundamental frequency from an analog signal. The disclosed concept further pertains to systems for removing a fundamental frequency from an analog signal.
2. Background Information
In many situations, current components indicative of system faults are of a much smaller magnitude than the magnitude of a line frequency component. When implemented on low-cost digital signal processors, the performance of fault detection algorithms is significantly impaired by the loss of resolution of such current components after the analog-to-digital conversion (ADC) process. This problem can be alleviated by removing the line frequency component prior to ADC and by utilizing the full dynamic range of the ADC for the current components indicative of system faults. Known conventional techniques involving the removal of sinusoidal components often utilize notch filters set at the particular frequency of interest. However, these notch filters, in addition to canceling the desired frequency component, often remove or attenuate signal components of interest that are sufficiently close to the desired frequency. This is primarily due to the fact that the supply frequency from the utility can vary from the nominal value (e.g., without limitation, 50 Hz; 60 Hz). The conventional filters also cannot be used in applications where variable frequency motor drives are employed.
There is room for improvement in filters for removing a fundamental frequency from an analog signal.
There is also room for improvement in methods of removing a fundamental frequency from an analog signal.
There is further room for improvement in systems for removing a fundamental frequency from an analog signal.